By Lt. Adrienne Eastlake, MS, RS/REHS
Engineered nanoparticles are unique. They are generally smaller than both red blood cells and viruses, don’t weigh much, and have a great amount of surface area proportionate to their size. These particles are increasingly used in a wide variety of products, ranging from cosmetics to concrete. Workers who make and use engineered nanoparticles would be the first potentially exposed to any new material. So, it seems important to be able to determine whether workers are exposed to these materials in an occupational setting, right?
Because of the unique properties of these materials, it can be a challenge to identify whether there is a potential for worker inhalation exposure. Why? Well, first because they are so small it is difficult to see nanoparticles unless we use electron microscopy, which is time consuming and expensive. Second, even if we collect a sample and weigh it, there may not be enough mass to be detected. Traditional industrial materials, composed of particles that are larger in size, do not pose such hurdles for sampling and analyzing. So with these challenges, how do we identify if nanomaterials present the potential for occupational inhalation exposure in a workplace?
NIOSH has been researching this very question for over a decade. In 2009, based on both laboratory research and field investigations, NIOSH developed and was the first to recommend using the nanoparticle emission assessment technique (NEAT).,, This technique made use of a condensation particle counter that could be used to identify tasks that result or can result in the emission of nanoparticles into the surrounding air. Then, task-based filter samples were used to confirm the presence of these materials, using both laboratory elemental analysis and electron microscopy. This initial approach didn’t effectively address the potential for background contamination from incidental nano-sized particles (unrelated to emissions from the work process being studied) or exposure over a full workday. In addition, it was heavily dependent on the use of direct reading instruments (DRIs), which are nonspecific aerosol monitors and subject to interferences such as background incidental particles. So, based on the need to surmount these limitations, and a desire to learn more about potential occupational exposures, NEAT was updated.
Refinement of the Nanoparticle Emission Assessment Technique into the Nanomaterial Exposure Assessment Technique (NEAT 2.0) was recently published in the Journal of Occupational and Environmental Hygiene. This is a more robust sampling strategy that places a stronger emphasis on…Click here to read the rest of the blog post.